The trend of top five types of poisonings in hospitalized patients based on ICD‐10 in the northeast of Iran during 2012–2018: A cross‐sectional study

Abstract Background and Aims Poisoning remains a major health issue in developing countries with high morbidity and mortality rates; also it is one of the most common causes of admission to hospitals. This study aimed to investigate the trend of the top five types of poisonings in hospitalized patients according to the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD‐10) in Imam Reza hospital, Mashhad, Iran. Methods This was a cross‐sectional study performed from March 20, 2012, until September 22, 2018. We collected data from all patients hospitalized for poisoning admitted to the poisoning center at Imam Reza hospital in northeast Iran. ICD‐10 was adopted to categorize all types of poisonings (T36‐T65). The results obtained were analyzed by SPSS 16. Results Thirty‐four thousand eight hundred and ten cases were included. The mean age of the patients was 29.64 ± 14.69 years, of them, 50.7% were males. Benzodiazepine poisoning (T42.4) has the highest frequency among other subcategories and it was more common among females (60.5%). Opium poisoning (T40.0) has the highest mortality rate (5.4%) among other subcategories that is more common in males (72.0%). The mortality associated with narcotics was the highest frequency (2.7%). Suicide (83.6%) was the most common cause of poisoning. Most poisonings occurred in summer (27.4%). Conclusion These findings could help health care managers and policymakers develop prevention and educational programs to reduce these poisonings and limit people's easy access to drugs and substances.


| INTRODUCTION
Poisoning is defined as the harm a person is subject to when exposed to drugs, chemicals, or toxins. It is also considered a threat to public health that can lead to morbidity and mortality worldwide. 1,2 Poisoning is considered to be the second leading cause of deathrelated injury in the United States. 3 Every year, many people around the world are admitted to emergency rooms due to various types of poisoning. 4 Due to changes in people's lifestyles and their social behavior, the trend of poisoning is changing day by day in today's societies. 5 Drug poisoning is more common than other poisonings and it can be used intentionally (suicide) or unintentionally (accidental). 6 Drug abuse is a serious problem in many countries, especially among young men. 7 Behavioral factors such as cigarette and cannabis use and psychological and personality factors including depression and impulsive and anxious traits, increase the risk of drug abuse day by day, which can lead to drug poisoning. 8,9 In developing countries, the prevalence of acute intentional and unintentional poisoning varies from 0.2 to 9.3 cases per 1000 individuals annually. 10 In addition, in recent decades, the rate of morbidity and mortality due to poisoning has almost tripled and about 90% of this morbidity and mortality is due to drugs. 11 According to a World Health Organization report, approximately 193,460 people died from unintentional poisoning, with 84% of these deaths occurring in low-and middle-income countries. 12 The pattern of poisoning differs among countries and regions, and this difference depends on various factors such as geography, accessibility, and availability of poison, social, economic, cultural, religious, and legal conditions. [13][14][15][16] In Iran, poisoning is one of the most common causes of hospitalization and the second leading cause of mortality. 17 In this developing country, drugs and chemicals are almost easily available to people 18 and poisoning with drugs and chemicals is common. 4,15 Natural toxins such as poisonous plants and animals are present in most parts of the country, and drug abuse/addiction is also common. 19 In Iran, most poisonings occur intentionally and among individuals aged 21-30 years. 4,20,21 From 1990 to 2015, it is estimated that 40,586 poison-related deaths occurred throughout Iran. 15 In addition, in this developing country, the highest frequency of death due to drug poisoning occurs in men. 4 According to the study on the prevalence of poisoning in Northeastern Iran (Khorasan Razavi, Mashhad) from 2004 to 2013, it was determined the rate of poisoning was increased. 21 The use of diagnostic classification standards can help healthcare providers, policymakers, researchers, and patients to navigate, understand, and compare healthcare systems and services. 22,23 One of the used standards in the diagnostic classification is the International Statistical Classification of Diseases and Related Health Problems, the tenth revision (ICD-10), which has been made to classify diagnoses and other healthrelated data of patients hospitalized as alphanumeric codes. Using data coded according to the ICD-10 facilitates obtaining morbidity information in a standard format and enhances the collection, storage, and analysis of comparable data among countries. Awareness of the types and causes of poisonings based on ICD-10 can be effective in preventing them. Therefore, the purpose of this study was to investigate the trend of the first five causes of poisonings in northeastern Iran from 2012 to 2018. We collected retrospective data from all patients hospitalized for poisoning admitted to the poisoning center at Imam Reza hospital. All emergency and outpatients poisoning were excluded from the study. First, the data were cleaned. In the first step, the data was checked for possible duplicates based on the national identity, medical record number, age, and date of admission. Then the cases with incomplete or wrong-recorded ICD-10 codes of poisoning, wrong date of birth, and wrong date of discharge (compared to the date of admission) were omitted. Furthermore, any cases having wrong information due to incorrect coding were excluded. The population for the remaining years was interpolated using the population projection formula.

| RESULTS
Of the 46,202 patients, 11,392 were not included in the analysis because of having missing data on some variables or wrong coding during the registry. Of the 34,810 remaining patients, 50.7% of them were men.
The majority of the patients were married (54.4%). The mean age of the patients was 29.64 ± 14.69 years, with a range of 3 days to 97 years, and men were somehow older than women (31.98 ± 15.66 years and 27.56 ± 13.19 years, respectively). In addition, the mean length of hospital stay for poisoned patients was 2.1 ± 4.7 days (men = 2.5 ± 5.5 and women = 1.7 ± 3.6). The total number of poison-related deaths in the top five categories was 435 cases (320 males and 115 females). The distribution of poisonings in different seasons was similar (from 27.4% of cases in summer to 23.2% in winter) ( Table 1).
According to the codes blocks of the 19th chapter of ICD-10, the five most frequent ICD-10 categories and subcategories codes are presented in Table 2. The results of Table 2 show that the most common categories of poisoning were poisoning by antiepileptic, sedative-hypnotic, antiparkinsonism drugs (T42), narcotics and hallucinogens drugs (T40), nonopioid analgesics, antipyretics and anti-rheumatics drugs (T39), psychotropic drugs (T43) in descending order. Benzodiazepine poisoning (T42.4) had the highest frequency among other subcategories and it was more common among females than males (60.5% vs. 39.5%). Methadone poisoning (T40.3) was more common in men (67.2%). Opium poisoning (T40.0) has the highest mortality rate (5.4%) among other subcategories that is more common in males (72.0%). The mortality associated with narcotics had the highest frequency (2.7%).
The results in Figure 1 show that in general, poisoning with T40 drugs (such as Methadone and Opium) has increased and poisoning with T39 drugs (such as NSAIDs and 4-Aminophenol derivatives) has      to country, depending on the availability of toxic substances. 17,30 In this study, based on the top five categories, the highest frequency of poisoning was related to benzodiazepines (26.6%) and the highest incidence of poisoning was with this drug. Most of the people who were poisoned with benzodiazepines were women. Benzodiazepines are often used to treat anxiety, insomnia, and other conditions, and are more commonly prescribed to women than men.
Emergency department visits and overdose deaths involving benzodiazepines have increased significantly among women in recent years. 31 This finding can be attributed to the accessibility of pharmaceuticals products in Iran. Over-the-counter (OTC) access to benzodiazepines appears to play a major role in drug intoxication in the study population. Numerous studies have been performed in this regard in the past, and their findings are consistent with the findings of the present study. 20,25,27,32 The findings of the present study showed that poisoning by narcotics such as Opium (T40.0) and Methadone (T40.3) was common in men and some studies have been conducted in this regard that confirms this. 33,34 In Iran, morbidity, and mortality due to poisoning are more common in men due to easy access to medicine and drugs as well as their abuse. 4 A common cause of mortality in men was poisoning by narcotics, such as Opium (T40.0  4 Lund et al. aimed at epidemiological investigation of poisoned individuals hospitalized in Oslo and found that opioids are the most common causes of death. 6 In Iran, opium, and opium residue are the most common opioids, one of the reasons for which could be the place of Iran and Khorasan Razavi province on the transit path of drugs, including opium, which has facilitated access to this substance. In this study, we found that intentional self-harm (suicide) poisoning had the highest frequency among causes of poisonings. In addition, most of the poisoned patients were young people (almost 30 years old). It may also be due to easy access to drugs in Iran. Thus, policymakers should have more control over the sale of drugs without a physician's prescription. Numerous studies have been conducted that confirm the findings of the present study. 4,15,20,21,26 There are numerous factors such as family conflicts, financial instabilities, unemployment, friendship losses, substance abuse, education failures, health-related quality of life, legal problems, and mental health problems such as depression is associated with suicide from a medication overdose. 35 important role in drug poisoning. Also, they found that 77.1% of the cases were intentionally poisoned (with intent to commit suicide). 25 The findings of our study were consistent with this study.
According to the findings of the present study, summer (27.7), spring (26.1), winter (23.2), and autumn (23.0) have the highest frequency of poisonings, respectively. These findings were consistent with the findings of the study by Mehrpour et al. 20 One of the notable limitations in this study was that only patients for whom a hospitalized medical record was created and whose diagnosis was coded were included in the study, and all of the emergency and outpatients poisoning were not considered in this study, which could affect the data comprehensiveness. Another notable limitation is that the coding quality of poisonings was not examined in this study. However, since the coding of medical records in the hospital under study is done by health information management specialists, the researchers assumed the high accuracy of the assigned codes. In the review of the top five categories of poisoning, many other subcategories were observed, which could be considered

| CONCLUSION
In this study, it was found that poisoning due to some drugs such as benzodiazepine and methadone was the most common cause of poisoning. Most of the patients with poisoning are young and they had intentional self-harm. It seems that reducing the availability of OTC drugs and decreasing the prescription of unnecessary pharmaceutical compounds, drug trafficking control, addiction rehabilitation therapies, and suicide prevention programs for younger ones can be helpful in poisoning reduction in this age group in this part of the country. Therefore, policymakers and healthcare managers can adopt the necessary programs and policies to prevent and control poisonings.

CONFLICTS OF INTEREST
The authors declare no conflicts of interest.

TRANSPARENCY STATEMENT
Alireza Banaye Yazdipour confirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request. The data are not publicly available due to privacy or ethical restrictions.

ETHICS STATEMENT
The study was approved by the Ethical Committee of Mashhad